We ran into some problems with the new non-native widget, and in the end decided to revert to using QVTKOpenGLNativeWidget everywhere (see the thread at How to decide between QVTKOpenGL{Native}Widget?). The common wisdom right now seems to be to use QVTKOpenGLNativeWidget unless you need stereo rendering.
I can have a go with your test case + latest drivers on my test Windows laptop after lunch. It has an older Intel GPU though. Do you know if you only saw this with UDH 620/630, not with older GPUs? I have a laptop with UHD620 as well, but I recently switched it to Linux 